(a) Field
The invention relates to a trench forming method, a metal wiring forming method, and a method of manufacturing a thin film transistor array panel. More particularly, the invention relates to a trench forming method which allows etching at a high selectivity and prevents an interior of a trench from being contaminated, a metal wiring forming method, and a method of manufacturing a thin film transistor array panel.
(b) Description of the Related Art
In general, a thin film transistor (“TFT”) is used as a switching device for independently driving each pixel in a flat panel display device such as a liquid crystal display or an organic light emitting diode display. A thin film transistor array panel of the flat panel display includes the thin film transistor, a pixel electrode connected to the thin film transistor, a gate line for transferring a gate signal to the thin film transistor, a data line for transferring a data signal, and the like.
The thin film transistor includes a gate electrode connected to a gate line to receive a gate signal, a semiconductor layer formed on the gate electrode, a source electrode formed on the semiconductor layer and connected to a data line to receive a data signal, and a drain electrode formed to be spaced apart from the source electrode and connected to a pixel electrode. In this case, the gate line, the gate electrode, the data line, the source electrode, the drain electrode, and the like are formed with metal wirings.
In order to increase resolution, there have been studies toward enhancement of pixel integrity per unit area in a thin film transistor array panel. Studies on methods of using a high electron mobility oxide semiconductor or a low-resistance copper wiring are being made to process image signals at a high speed.
In this case, it is necessary to, after depositing an insulating layer of several micrometers, form a trench and form a copper wiring in the trench in order to realize a low-resistance copper wiring. When a photo etching process using an existing photosensitive film as a mask is used to form a trench, selectivity of etching is disadvantageously very low.
A method of performing etching by using a metal mask instead of a photosensitive film is being studied, but if a metal mask is used, residue is produced in a trench so that a bottom of the trench cannot be etched, causing residual films to be left.